I have the "One Ragged Hole" peep sight on my 5 1/2" Ruger Bisley 45 colt and it is GREAT. Sights are accurate and extremely fast to acquire the target. I have always favored peep sights on rifles and am happy to find them available for pistols. A fellow posted on the Ruger Forum some time back about making these himself, rather than buying them, but $19.95 doesn't seem that steep for two inserts. AND, simple to pop in or out if you want to vary peep size or go back to the blade.
Mike